Lattice infill patterns control the distribution of material inside a part, trading weight for mechanical performance by changing how load paths form through a structure. Classic work by Lorna J. Gibson and Michael F. Ashby Cambridge University Press shows that the effective modulus and strength of cellular solids scale with relative density: lattices that transmit loads primarily through member stretching exhibit near-linear scaling with density, while bending-dominated architectures show much stronger dependence on density and therefore lose stiffness faster as material is removed. This scaling explains why two designs with the same mass can have markedly different stiffness and strength.
Topology, orientation, and failure modes
Unit cell geometry and connectivity determine whether a lattice is stretch-dominated or bending-dominated, which in turn controls stiffness, strength, and anisotropy. Research led by Mark Brackett University of Sheffield demonstrates that octet-truss and other highly connected lattices behave more like continuum solids under load, giving higher stiffness per unit mass, while simpler beam or plate lattices are more compliant and concentrate bending stresses. Manufacturing realities—surface roughness, residual stress, and imperfect node fusion—introduce localized weaknesses that reduce the theoretical benefits; Brackett’s group emphasizes matching topology to the chosen additive process and post-processing strategy to preserve performance.
Applications, trade-offs, and broader impacts
Designers exploit lattice infill for aerospace and transport components to lower fuel use through mass reduction, and for biomedical implants to balance stiffness with porosity that promotes tissue in-growth. Scott J. Hollister University of Michigan has shown that controlled porosity and interconnectivity in implant lattices improve bone integration while avoiding stress shielding by tailoring stiffness. However, consequences include increased production complexity, potential recyclability challenges, and sensitivity to manufacturing variability. Lattices that maximize weight savings may also concentrate loads, increasing the risk of fatigue failure in cyclic applications; thus, functional requirements often force compromises between minimum mass and acceptable durability.
Understanding the interplay of topology, relative density, and process-specific limitations allows engineers to design lattice infills that meet target performance. Empirical validation and conservative safety factors remain essential because theoretical scaling laws assume ideal geometries, whereas real parts reflect the cultural and territorial realities of supply chains, available AM equipment, and regulatory requirements that shape which lattice strategies are practical in a given industry.